1. Field of Invention
This invention relates in general to refractive correction and in particular to a method and means of fabricating an improved permeable contact lens that mimics the native corneal structure.
2. Background Description of Prior Art
While significant advances have been achieved in the field of contact lens design and fabrication, many problems still exist. Of these, paramount of which is the fact that the polymers utilized are created as a solid or at best, as semi permeable solid structures. These structures reduce the available oxygen to the corneal surface, minimize tear and aqueous transport through the lens, and act as a nucleation point for protein buildup. The disclosed invention allows for situations that would enable the manufacture of a contact lens that would have a high oxygen permeability, while allowing the option of having either a lipid impermeable or lipid permeable functionality. This functionality will be of great importance in designing a therapeutic contact lens, in addition to a refractive contact lens. In either case, one would want a high degree of oxygen permeability as the cornea is an avascular membrane and receives its oxygen supply directly through the air. Any impediment that obstructs the corneal surface with direct contact with the surrounding air would be detrimental. Examination of the prior art has not revealed any technology, which approaches the novelty, efficacy, and ease of implementation that the disclosed invention teaches. Additionally, it is common for a contact lens to be constructed as completely homogenous or with a homogenous outer surface enclosing a hydrogel or polymeric interior, which means that the lens outer covering material is consistent throughout its structure. With the disclosed invention, it is now possible to create a contact lens structure that is made out of varying layers of differing polymer materials, with the possibility of interdispersement of trapped drug layers to maintain a localized point of contact with the desired drug or medication and the corneal surface. The degree of surface hydrophobocity and hydrophilicity could be engineered into the surface, along with the ability to restrain lipid transport into the lens structure from degrading optical clarity. One of the additional benefits of manufacturing by the described invention is that the base surface side (eye contact surface) of the contact lens could be made of a completely different material than there is on the outside surface of the contact lens. For instance, the base surface side (cornea contact surface) could be made hydrophilic to provide superior wetting while the outside (air contact surface) could be made hydrophobic and prevent the problem of ordinary contact lenses from having a degraded oxygen permeability. Materials that are generally incompatible with the eye could still be used to construct a contact lens, since they will not be coming into actual contact with the eye surface. A wide assortment of contact lenses could be constructed by utilizing this ability of the described invention. Again, any means of producing a polymer lens which reduces the diffusion rate of oxygen, reduces the effectiveness of the lens and could in the long term cause irreparable damage to the corneal surface. Subtle changes in the diffusion rate can cause significant loss in visual acuity. Also, nonnatural polymers can be rejected by the immune system. The disclosed invention, being of preferably benign genetically engineered collagen or other suitable polymer, yields a lens structure that is virtually indistinguishable to native natural corneal tissue. The process allows for the person's own native collagen to be harvested or grown and used to create the contact lens. This would enable a contact lens to be produced that is virtually guaranteed not to be rejected by a person's own immune system.